Display device having backlight

ABSTRACT

According to one embodiment, a display device includes a display panel including a first sub display area and a second sub display area, and an illumination device, wherein the illumination device includes a first light source opposed to the first sub display area, a second light source opposed to the second sub display area, and a partition positioned between the first and second light sources and the display panel, and the partition includes a first side surface surrounding the first light source, a second side surface surrounding the second light source, and a connector which connects the first side surface and the second side surface, and the connector is formed of curved surfaces, or two or more flat surfaces, or a combination of curved surfaces and flat surfaces.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/177,948, filed on Feb. 17, 2021, which is a continuation of Ser. No.16/738,622, filed on Jan. 9, 2020, which is a continuation of Ser. No.15/598,552, filed on May 18, 2017, which application is based upon andclaims the benefit of priority from Japanese Patent Application No.2016-099879, filed May 18, 2016, the entire contents of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to a display device.

BACKGROUND

As a kind of display devices, there is a commercially utilized structureincluding a liquid crystal display panel and a backlight with lightsources disposed immediately below thereof. There is a proposedtechnique that, when adjacent light sources in a backlight are allturned on, the total strength of the light is made substantially even.Furthermore, there is another proposed technique that, when an imagedisplayed in a head-up display, a range of the displayed image isrecognized to turn on light sources corresponding to the range in orderto reduce the power and to suppress heating. Furthermore, there isanother proposed technique that a direct backlight has step pyramidholes in a holder tapered from the light emitting element side to thelight emitting surface in order to reduce unevenness in the brightness.The direct backlight is also called straight fall type backlight.

When a light source array in which light sources are arranged at certainintervals is driven, it is required to reduce unevenness in thebrightness caused by a dim line with low brightness and a bright linewith high brightness. Furthermore, a display device including such anillumination device is required to suppress deterioration of displayquality caused by such unevenness in the brightness of the illuminationdevice.

SUMMARY

The present disclosure generally relates to a display device.

According to an embodiment, a display device includes a display panelincluding a first sub display area and a second sub display area, and anillumination device, wherein the illumination device includes a firstlight source opposed to the first sub display area, a second lightsource opposed to the second sub display area, and a partitionpositioned between the first and second light sources and the displaypanel, and the partition includes a first side surface surrounding thefirst light source, a second side surface surrounding the second lightsource, and a connector which connects the first side surface and thesecond side surface, and the connector is formed of curved surfaces, ortwo or more flat surfaces, or a combination of curved surfaces and flatsurfaces.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the structure of a display device ofan embodiment.

FIG. 2 shows an example of the structure of an illumination device and adisplay panel applicable to the embodiment.

FIG. 3 is a block diagram showing an example of the structure of thedisplay device to which a local dimming control is applied.

FIG. 4 is a perspective view of the display device of the embodiment ina disassembled manner.

FIG. 5 is a plan view showing an example of the structure of a partitionPT applied to an illumination device of FIG. 4.

FIG. 6 shows the distribution of the brightness when adjacent lightsources are turned on at the same time in the illumination device.

FIG. 7 is a cross-sectional view of an example of the structure of apartition, taken along line A-B of FIG. 5.

FIG. 8 is a cross-sectional view of an example of the structure of thepartition, taken along line A-C of FIG. 5.

FIG. 9 is a cross-sectional view of another example of the structure ofthe partition, taken along line A-B of FIG. 5.

FIG. 10A is a cross-sectional view of another example of the structureof the partition, taken along line A-B of FIG. 5.

FIG. 10B is a cross-sectional view of another example of the structureof the partition, taken along line A-B of FIG. 5.

FIG. 11 is a cross-sectional view of another example of the structure ofthe partition, taken along line A-B of FIG. 5.

FIG. 12 is a perspective view of another example of the structure of thepartition in a disassembled manner.

FIG. 13 is a cross-sectional view of an example of the structure of thepartition, taken along line D-E of FIG. 5.

FIG. 14 is a cross-sectional view of another example of the structure ofthe partition, taken along line A-B of FIG. 5.

FIG. 15 is a cross-sectional view of another example of the structure ofthe partition, taken along line A-B of FIG. 5.

FIG. 16 is a cross-sectional view of another example of the structure ofthe partition, taken along line A-B of FIG. 5.

FIG. 17 is a plan view of an example of the arrangement of an opticaladjustor in ridges.

FIG. 18 is a plan view of another example of the arrangement of theoptical adjustor in the ridges.

FIG. 19 is a plan view of another example of the arrangement of theoptical adjustor in the ridges.

FIG. 20 is a plan view of another example of the arrangement of theoptical adjustor in the ridges.

FIG. 21 is an example of the application of the display device of theembodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, a display device comprising: adisplay panel including a first sub display area and a second subdisplay area; and an illumination device which illuminates the displaypanel, wherein the illumination device includes a first light sourceopposed to the first sub display area, a second light source opposed tothe second sub display area, and a partition positioned between thefirst and second light sources and the display panel, and the partitionincludes a first side surface surrounding the first light source, asecond side surface surrounding the second light source, and a connectorwhich connects the first side surface and the second side surface, andthe connector is formed of curved surfaces, or two or more flatsurfaces, or a combination of curved surfaces and flat surfaces.

In general, according to one embodiment, a display device comprising: adisplay panel including a first sub display area and a second subdisplay area; and an illumination device which illuminates the displaypanel, wherein the illumination device includes a first light sourceopposed to the first sub display area, a second light source opposed tothe second sub display area, and a partition positioned between thefirst and second light source and the display panel, and the partitionincludes a side surface surrounding the first light source and thesecond light source, respectively, and an upper surface opposed to thedisplay panel, and an optical adjustor which is positioned on the uppersurface to diffuse or absorb light.

In general, according to one embodiment, a display device comprising: adisplay panel including a first sub display area and a second subdisplay area; and an illumination device which illuminates the displaypanel, wherein the illumination device includes a first light sourceopposed to the first sub display area, a second light source opposed tothe second sub display area, and a partition positioned between thefirst and second light source and the display panel, and the partitionincludes a first ridge and a third ridge extending in a first directionand a second ridge extending in a second direction to cross the firstridge and the third ridge in a plan view, and recesses positioned at afirst crossing point of the first ridge and the second ridge and asecond crossing point of the third ridge and the second ridge, and aprojection positioned between the first crossing point and the secondcrossing point.

Embodiments will be described hereinafter with reference to theaccompanying drawings. Incidentally, the disclosure is merely anexample, and proper changes within the spirit of the invention, whichare easily conceivable by a skilled person, are included in the scope ofthe invention as a matter of course. In addition, in some cases, inorder to make the description clearer, the widths, thicknesses, shapes,etc. of the respective parts are schematically illustrated in thedrawings, compared to the actual modes. However, the schematicillustration is merely an example, and adds no restrictions to theinterpretation of the invention. Besides, in the specification anddrawings, the structural elements having functions, which are identicalor similar to the functions of the structural elements described inconnection with preceding drawings, are denoted by like referencenumerals, and an overlapping detailed description is omitted unlessnecessary.

Initially, a display device of an embodiment will be explained.

FIG. 1 is a block diagram showing a display device DSP of the presentembodiment.

As in FIG. 1, the display device DSP includes a controller 10, displaypanel PNL, and illumination device IL which illuminates the displaypanel PNL. The controller 10 includes a signal processor 20, displaypanel driver 40 which controls the drive of display panel PNL, andillumination device controller 60 which controls the drive ofillumination device IL.

The signal processor 20 receives an input signal SGI of an image from animage output unit 11, sends an output signal SGO to each unit in thedisplay device DSP to control the operation of the display device DSP.The signal processor 20 is connected to the display panel driver 40 andthe illumination device controller 60. Here, the signal processor 20corresponds to a processor to control the operation of the display panelPNL and the illumination device IL. The signal processor 20 processesthe input signal SGI and generates the output signal SGO andillumination device control signal SGIL. The signal processor 20 outputsthe output signal SGO to the display panel driver 40 and outputs theillumination device control signal SGIL to the illumination devicecontroller 60.

The display panel PNL displays an image based on the output signal SGOfrom the signal processor 20. The display panel PNL includes a pluralityof pixels PX arranged in a matrix. As will be described later, eachpixel PX includes several subpixels each of which includes a switchingelement and the like.

The display panel driver 40 includes a signal output circuit 41 and ascan circuit 42. The signal output circuit 41 is electrically connectedto the display panel PNL through a signal line SL. The scan circuit 42is electrically connected to the display panel PNL through a scan lineGL. The display panel driver 40 maintains an image signal with thesignal output circuit 41 and sequentially outputs the image signal tothe display panel PNL. Furthermore, the display panel driver 40 selectssubpixels in the display panel PNL with the scan circuit 42 and controlson/off of switching elements to control the operation (lighttransmissivity) of the subpixels.

FIG. 2 shows an example of the structure of the illumination device ILand the display panel PNL applicable to the present embodiment. In theexample depicted, a first direction X, second direction Y, and thirddirection Z are orthogonal to each other; however, they may cross at anangle other than 90° . The X-Y plane defined by the first direction Xand the second direction Y is substantially parallel to the mainsurfaces of optical members such as display panel PNL and illuminationdevice IL. The third direction Z corresponds to a layer direction of theillumination device IL and the display panel PNL and a travellingdirection of light emitted from the illumination device IL.

In the example depicted, the display panel PNL is a liquid crystaldisplay panel which includes a first substrate SUB1, second substrateSUB2, and liquid crystal layer LC held between the first substrate SUB1and the second substrate SUB2. A polarizer PL1 is disposed on the rearsurface side of the first substrate SUB1. A polarizer PL2 is disposed onthe front surface side of the second substrate SUB2. For example,absorption axes of the polarizers PL1 and PL2 are orthogonal to eachother in the X-Y plane. Here, the side of the display panel PNL wherethe illumination device IL is disposed is referred to as the rearsurface side, and the opposite side to the rear surface side is referredto as the front surface side.

The display panel PNL includes a display area DA on which an image isdisplayed. The display panel PNL includes a plurality of pixels PXarranged in a matrix in the first and second directions X and Y withinthe display area DA. A pixel PX includes, for example, first subpixelSPX1, second subpixel SPX2, and third subpixel SPX3. The first subpixelSPX1 includes, for example, a red color filter to display red. Thesecond subpixel SPX2 includes, for example, a green color filter todisplay green. The third subpixel SPX3 includes, for example, a bluecolor filter to display blue.

The first substrate SUB1 includes scan lines GL (gate lines) and signallines SL (data lines or source lines) crossing the scan lines GL. Eachscan line GL extends to the outside of the display area DA to beconnected to the scan circuit 42. Each signal line GL extends to theoutside of the display area DA to be connected to the signal outputcircuit 41. Both the scan circuit 42 and the signal output circuit 41are controlled by the image data used to the image display on thedisplay area DA.

Each subpixel includes a switching element SW (for example, thin filmtransistor), pixel electrode PE, and common electrode CE. The switchingelement SW is electrically connected to the scan line GL and the signalline SL. The pixel electrode PE is electrically connected to theswitching element SW. The common electrode CE is opposed to a pluralityof pixel electrodes PE. The pixel electrode PE and common electrode CEare function as a driver electrode which drives the liquid crystal layerLC. The pixel electrode PE and the common electrode CE are formed of atransparent conductive material such as indium tin oxide (ITO) or indiumzinc oxide (IZO).

The illumination device IL is disposed on the rear surface of thedisplay panel PNL and emits light to the display panel PNL. Theillumination device IL includes an illumination area IA opposed to thedisplay area DA. The illumination device IL includes a light source LSarranged in a matrix in the illumination area IA. The light source LSis, for example, a light emitting diode which emits white light;however, no limitation is intended thereby. As a light source LSemitting white light may be a one-chip light emitting diode which emitsred, green, and blue, or a combination of blue or near-ultraviolet lightemitting diode and a fluorescence. Such a light source LS can controlthe brightness depending on the amount of current supplied.

For example, one light source LS is disposed to be opposed to a subdisplay area including m x n pixels PX. Note that m and n are positiveintegers where m is the number of the pixels PX aligned in the firstdirection X and n is the number of the pixels PX aligned in the seconddirection Y. Each light source LS can be turned on/off individually.Thus, the illumination device IL can form a sub illumination area whichcan be turned on/off individually in the illumination area IA. The subillumination area includes at least one light source LS. The subillumination area can be formed as various shapes such as a band-likeshape extending in the first direction X, or a band-like shape extendingin the second direction Y, or a matrix arranged in the first and seconddirections X and Y in the X-Y plane.

Now, a local dimming control will be explained.

FIG. 3 is a block diagram showing an example of the structure of thedisplay device DSP to which the local dimming control is applied.

The illumination device IL includes sub illumination areas IA11, IA12, .. . arranged in a matrix within the illumination area IA. The displaypanel PNL includes sub display areas DA11, DA12, . . . arranged in amatrix within the display area DA. As explained with reference to FIG.2, each sub illumination area comprises one or more light sources. Eachsub display area is opposed to the corresponding sub illumination areaand includes m x n pixels PX. The brightness of the sub illuminationarea can be controlled on the basis of the current value supplied to thelight source. Thus, by changing the current value of the light source ofeach sub illumination area, the brightness thereof can be changed. Lightemitted from each sub illumination area illuminates the correspondingsub display area. Thus, in the display area DA, the brightness of thesub illumination areas which illuminate the sub display areas includinglow gradation pixels is set low, and the brightness of the subillumination areas which illuminate the sub display areas including highgradation pixels is set high. Thereby, the contrast ratio of the imagedisplayed in the display area DA can be improved.

Now, an example of the control will be explained briefly. As shown inFIG. 1, an input signal SGI as the data of the image to be displayed isinput in the signal processor 20 from the image output unit 11. Thesignal processor 20 includes a timing generator 21, image processor 22,image analyzer 23, and light source driving value selector 24.

The timing generator 21 synchronizes the image displayed by the displaypanel PNL and the drive of the illumination device IL. That is, thetiming generator 21 processes the input signal SGT to send a signal usedfor the timing synchronization of the display panel PNL and theillumination device controller 60 by each frame to the display paneldriver 40 and the illumination device controller 60.

The image processor 22 performs processes to display an image on thedisplay panel PNL on the basis of the drive of the illumination deviceIL. That is, the image processor 22 processes the input signal SGI togenerate an output signal used to determine the display gradation ofeach of the first to third sub pixels and processes the display data tobe output to the display panel driver 40 in order to display the imagecorresponding to the drive of the light source. The image analyzer 23processes the input signal SGI to analyze the image displayed in subillumination areas IA11, IA12, . . individually. The light sourcedriving value selector 24 selects a driving value of each light sourceon the basis of the data analyzed by the image analyzer 23, sends thedata of the brightness of each sub pixel to the image processor 22, andcontrols the illumination device controller 60.

FIG. 4 is a perspective view of the display device DSP of the presentembodiment in a disassembled manner.

The illumination device IL is disposed in the rear surface side of thedisplay panel PNL. The illumination device IL includes light sources LS,a partition PT disposed between the light sources LS and the displaypanel PNL, and a light diffusing layer DP disposed between the partitionPT and the display panel PNL. The light sources LS are arranged in amatrix in the first and second directions X and Y. The light sources LSare each mounted on a circuit substrate LFPC.

The partition PT includes light guides LG which guide the light fromeach light source LS to the light diffusing layer DP. The light guidesLG are formed in a matrix in the first and second directions X and Y tobe opposed to the light sources LS. One light guide LG is opposed to onelight source LS. Here, one light source LS includes at least one lightemitting element such as light emitting diode (LED).

Now, the structure of the light guides LG will be explained withreference to one thereof.

A light guide LG includes an opening OP1 opposed to a light source LS,opening OP2 opposed to the light diffusing layer DL, and side surfacesP10 surrounding the light source LS. In the example depicted, the lightguide LG includes four side surfaces P10 surrounding one light sourceLS. Furthermore, each of the openings OP1 and OP2 is quadrangular andthe area of opening OP1 is less than that of opening OP2. Note that, forexample, the area of opening OP1 is equal to or more than the area oflight source LS, and the shape of opening OP1 is arbitrarily determinedto conform to the outer shape of light source LS. Thus, the light sourceLS is fit in the opening OP1. Such a light guide LG is formed in afrustum expanding from the light source LS to the light diffusing layerDP.

Note that, in this example, the number of side surfaces P10 surroundingone light source LS is four; however, no limitation is intended thereby.Furthermore, the shape of each of the openings OP1 and OP2 is a square;however, it may be a circle, ellipse, or any other polygonal shape.

FIG. 5 is a plan view showing an example of the structure of thepartition PT applied to the illumination device IL of FIG. 4.

Here, the structure of the partition PT will be explained with referenceto the light guides LG1 and LG2 corresponding to the light sources LS1and LS2. The partition PT includes side surfaces P11 to P14 surroundinga light source LS1, side surfaces P21 to P24 surrounding a light sourceLS2, and connector P3 connecting the side surface P11 and P21. The sidesurfaces P11 and P21 are arranged in the second direction Y. That is,the connector P3 is a connector of one side surface P11 of the four sidesurfaces P11 to P14 and one side surface P21 of the four side surfacesP21 to P24.

The partition PT includes, in a plan view, a ridge RG1 extending in thefirst direction X and a ridge RG2 extending in the second direction Y.One ridge RG1 continuously extends from one end to the other end of thepartition PT in the first direction X. Furthermore, one ridge RG2continuously extends from one end to the other end of the partition PTin the second direction Y. The ridges RG1 and RG2 cross each other in alattice. The connector P3 is disposed in the ridge RG1.

Referring to a part of the ridges RG1 and RG2 surrounding the lightsource LS1, the ridge RG1 has a length L1 in its part corresponding tothe light source LS1 and the right RG2 has a length L2 in its partcorresponding to the light source LS1. The lengths L1 and L2 may beequal or may be different. In the example depicted, the length L1 isgreater than the length L2; however, the length L2 may be greater thanthe length L1.

Note that the light sources LS1 and LS2 correspond to, for example, subdisplay areas DA11 and DA12 shown in FIG. 3. Here, each of the lightsources LS1 and LS2 is turned on/off with the brightness correspondingto the gradation value of the image data used to drive the sub displayareas DA11 and DA12 in synchronization with the image display on the subdisplay areas DA11 and DA12.

FIG. 6 shows the distribution of the brightness when adjacent lightsources are turned on at the same time in the illumination device IL.FIG. 6(a) is a schematic cross-sectional view including the lightsources LS1 and LS2, partition PT, and light diffusing layer DP, FIG.6(b) is a schematic cross-sectional view including the light sources LS1and LS2 and the partition PT, and FIG. 6(c) schematically shows thedistribution of the brightness of the light passing the light diffusinglayer DP when the light sources LS1 and LS2 are turned on at the sametime.

The distribution of the brightness when the light source LS1 alone isturned on is depicted by a hatch of lines slanting to right in thefigure, and the brightness becomes substantially even in the proximityof the center where the position immediately above the light source LS1is included and gradually decreases when closing to the proximity of theboundary B between the light sources LS1 and LS2. In the exampledepicted, given that the brightness in the proximity of the center is100%, the brightness becomes 50% in the proximity of the boundary B. Thedistribution of the brightness when the light source LS2 alone is turnedon is depicted by a hatch of lines slanting to the left in the figure,and the brightness changes in the same manner as the light source LS1.Thus, the distribution of the brightness when the light sources LS1 andLS2 are turned on at the same time is depicted as in the part surroundedby the solid line in the figure, and substantially 100% brightness canbe obtained not only in the parts immediately above the light sourcesLS1 and LS2 but also in the boundary B, and the distribution of thebrightness can be achieved uniformly. Therefore, when the light sourcesLS1 and LS2 are turned on at the same time, the distribution of thebrightness as depicted is desirable.

On the other hand, as to the distribution of the brightness of each ofthe light sources LS1 and LS2, if the brightness in the proximity of theboundary B is less than 50%, when the light sources LS1 and LS2 areturned on at the same time, the brightness becomes less than 100% in theproximity of the boundary B, and as a result, a dim line of lowbrightness appears in the boundary B.

Furthermore, as to the distribution of the brightness of each of thelight sources LS1 and LS2, if the brightness in the proximity of theboundary B is more than 50%, when the light sources LS1 and LS2 areturned on at the same time, the brightness becomes more than 100% in theproximity of the boundary B, and as a result, a bright line of highbrightness appears in the boundary B.

The distribution of the brightness of each light source differsdepending on conditions such as an angle of light exiting from the lightsource, position and height of each light guide LG, and aspect ratio inthe X-Y plane. Furthermore, in an light source array in which some lightsources LS, the brightness in the proximity of adjacent light sources LSdiffers depending on conditions such as distribution of the brightnessof each light source, gap between adjacent light sources, gap betweenadjacent light guides LG. Thus, in order to achieve even distribution ofthe brightness in the X-Y plane of the illumination device IL, or 50%brightness in the proximity of the boundary B, various designrestrictions must be considered.

For example, in the illumination device IL of FIG. 5, a dim line or abright line may appear immediately above the ridges RG1 and RG2, or adim line may appear immediately above either one of the ridges RG1 andRG2 and a bright line may appear immediately above the other. In orderto suppress such unevenness in the brightness, the present embodimentadopts following structural examples.

FIG. 7 is a cross-sectional view of an example of the structure of thepartition PT, taken along line A-B of FIG. 5. In the example depicted,the connector P3 is formed of curved surfaces. Note that the curvedsurfaces may be ellipse surfaces, paraboloid surfaces, sphericalsurfaces, or non-spherical surfaces. The side surfaces P11 and P21 areflat surfaces. Here, given that a surface parallel to the X-Y planeincluding exiting surfaces E1 and E2 of the light sources LS1 and LS2 isa reference surface Rf1, the side surfaces P11 and P21 are inclinedsurfaces with respect to the reference surface Rf1. For example, aninclination angle θ11 of the side surface P11 corresponds to an angleformed by the side surface P11 and the reference surface Rfl and is anacute angle. On the other hand, an inclination angle θ31 of theconnector P3 corresponds to an angle formed by a tangential line of theconnector P3 and the reference surface Rfl and is an acute angle. Theinclination angle θ11 is different from the inclination angle θ31. Asbeing depicted by solid lines in the figure, the inclination angle θ11of the side surface P11 is greater than the inclination angle θ31 of theconnector P31. As being depicted by dotted lines in the figure, theinclination angle θ11 of the side surface P11 is less than theinclination angle θ32 of the connector P3. Here, angle θ0 formed by aline L connecting the top T of the side surface P11 and the bottom C ofthe side surface P13 and the reference surface Rf1 is less than theinclination angle θ11. Furthermore, the angle θ0 is greater than theinclination angle θ31 and is less than the inclination angle θ32.

In the example depicted, the side surfaces P11 and P21 and the connectorP3 are formed integrally. The side surfaces P11 and P21 and theconnector P3 are formed of the same material and form reflectivesurfaces having substantially equal reflectivity. Such reflectivesurfaces can be formed of a metal layer or a resin layer of color ofhigh reflectivity such as white. Note that, for example, a hollow spaceis provided between the side surfaces P11 and P21; however, nolimitation is intended thereby. For example, a cross-sectional shape ofthe wall may have the side surfaces P11 and P21 and the connector P3,and in that case, the wall may be formed of a highly reflective metal orresin or a highly reflective metal or resin layer may be provided withthe surface of the wall. Furthermore, the side surfaces P11 and P12 andthe connector P3 may be formed of different materials, and in that case,the reflectivity of the side surfaces P11 and P21 may differ from thatof the connector P3.

In this embodiment, the connector P3 connecting the side surfaces P11and P21 adjacent to each other has an inclination angle which isdifferent from that of the side surface P11. For example, in a casewhere a dim line appears immediately above the ridge RG1 where theconnector P3 is disposed, it is effective to set the inclination angleθ31 greater than the inclination angle θ11. In such a structuralexample, the light exiting from substantially the entire area of theexiting surface E1 can be guided to the position immediately above theridge RG1. Especially, in the exiting surface E1, light emitted from theposition in the proximity of the bottom C of the side surface P13 is, asdepicted by the line L in the figure, guided to the position immediatelyabove the ridge RG1 without being blocked by the connector P3. Thus, adim line appearing immediately above the ridge RG1 can be suppressed.Furthermore, the connector P3 with the inclination angle θ31 formedsmall is curved as almost a flat surface parallel to the referencesurface Rf1. Thus, the light diffused by the light diffusing layer DP ispartly diffused toward the connector P3 and is directly reflected to thelight diffusing layer DP. Thereby, the appearance of the dim line can besuppressed.

Furthermore, in a case where a bright line appears immediately above theridge RG1 where the connector P3 is disposed, it is effective to set theinclination angle θ32 greater than the inclination angle θ11. In such astructural example, the connector P3 can block a part of the lightemitting from the exiting surface E1. Thus, the amount of light guidedto the position immediately above the ridge RG1 is decreased and theappearance of bright lines can be suppressed. Furthermore, the connectorP3 with the inclination angle θ32 formed large scatters the lightdiffused by the light diffusing layer DP. Thereby, the amount of lightredirected to the light diffusing layer DP is decreased and theappearance of the bright line can be suppressed.

Therefore, the illumination device IL of the present embodiment cansuppress unevenness of the brightness. Furthermore, the display deviceDSP with the illumination device IL of the present embodiment cansuppress degradation in the display quality caused by the unevenness ofthe brightness of the illumination device IL.

FIG. 8 is a cross-sectional view of an example of the structure of thepartition PT, taken along line A-C of FIG. 5. In the example depicted,the ridges RG1 and RG2 have different cross-sectional shapes. In theexample depicted, the ridge RG1 has a cross-sectional shape of theconnector P3 connecting the side surfaces P11 and P21, and the ridge RG2has a cross-sectional shape of the connector P4 connecting the sidesurfaces P22 and P41. The ridge RG1 has a height H1 measured from thereference surface Rfl and the ridge RG2 has a height H2 measured fromthe reference surface Rf1, where the height H1 is different from theheight H2. In the example depicted, the height H1 is greater than theheight H2. Furthermore, the connector P3 forming the ridge RG1 is, asdepicted by dotted lines in FIG. 7, used in a case where the inclinationangle θ32 is greater than the inclination angle θ11, and the connectorP4 forming the ridge RG2 is, as being depicted by solid lines in FIG. 7,used in a case where the inclination angle θ31 is less than theinclination angle θ11. The curvature of the connector P3 or P4 and theheight of the ridge RG1 or RG2 may be set as needed according to theratio between the length L1 and the length L2 and/or the shape of thelight guides LG.

As shown in FIG. 5, in the structure where the ridges RG1 and RG2surrounding their light sources have different parts lengths, the degreeof expansion of light in the first direction X and the degree ofexpansion of light in the second direction Y may differ, and there maybe a case where a dim line may appear in either one of the boundarybetween light sources adjacent in the first direction X and the boundarybetween light sources adjacent in the second direction Y, and a brightline may appear in the other. In such a case, the structure of FIG. 8 iseffective. For example, in a case where a bright line appearsimmediately above the ridge RG1 and a dim line appears immediately abovethe ridge RG2, the connector P3 forming the ridge RG1 blocks anddiffuses the light from the light source LS2 to suppress the appearanceof bright line, and the connector P4 forming the ridge RG2 guides thelight from the light source LS2 to the position immediately abovethereof to suppress the appearance of dim line. Thus, the unevenness ofbrightness can be suppressed.

FIG. 9 is a cross-sectional view showing another example of thestructure of the partition PT, taken along line A-B of FIG. 5. Ascompared to the structure of FIG. 7, the structure of FIG. 9 includesthe connector P3 formed of two or more flat surfaces.

In the example depicted, the connector P3 includes a first surface P31,second surface P32, and third surface P33. The first, second, and thirdsurfaces P31 to P33 are flat surfaces. The first surface P31 isconnected the side surface P11 and has an inclination angle which isdifferent from that of the side surface P11. The third surface P33 isconnected to the side surface P21 and has an inclination angle which isdifferent from that of the side surface P21. The second surface P32 isconnected to the first surface P31 and the third surface P33. The sidesurfaces P11 and P21 and the connector P3 are formed of the samematerial and form reflective surfaces having substantially equalreflectivity. Note that the connector P3 may be formed of a materialwhich is not used in the side surfaces P11 and P21 and may have thereflectivity different from that of the side surfaces P11 and P21.

In such a structure, the aforementioned advantages can be achieved.

FIG. 10A is a cross-sectional view showing another example of thestructure of the partition PT, taken along line A-B of FIG. 5. Ascompared to the example of FIG. 7, the structure of FIG. 10A includesthe connector P3 formed of a combination of curved surfaces and flatsurfaces.

In the example depicted, the first surface P31 and the third surface P33are curved surfaces, and the second surface P32 is a flat surface. Notethat, as will be explained later, the first surface P31 and the thirdsurface P33 are downward concaved surfaces; however, they may be upwardconvex surfaces. Furthermore, in the example depicted, the secondsurface P32 connects the first surface P31 and the third surface P33;however, the first surface P31 and the third surface P33 may beconnected directly by omitting the second surface P32.

In such a structure, the aforementioned advantages can be achieved.

FIG. 10B is a cross-sectional view showing another example of thestructure of the partition PT, taken along line A-B of FIG. 5. Ascompared to the example of FIG. 10A, the structure of FIG. 10B includesthe first surface P31 and the third surface P33 are upward convexsurfaces.

As in the example of FIG. 10A, in the example depicted, the firstsurface P31 and the third surface P33 are curved surfaces and the secondsurface P32 is a flat surface. Furthermore, in the example depicted, thesecond surface P32 connects the first surface P31 and the third surfaceP33; however, the first surface P31 and the third surface P33 may beconnected directly by omitting the second surface P32.

In such a structure, the aforementioned advantages can be achieved.

FIG. 11 is a cross-sectional view of another example of the structure ofthe partition PT, taken along line A-B of FIG. 5. As compared to theexample of FIG. 7, the structure of FIG. 11 includes the partition PTwith an optical adjustor DM1.

In the example depicted, the partition PT includes an upper surface USconnecting the side surfaces P11 and P21. The upper surface US is a flatsurface along the X-Y plane and is opposed to the display panel PNL andthe light diffusing layer DP. The optical adjustor DM1 is positioned onthe upper surface US. In the example depicted, the optical adjustor DM1is disposed in the entire surface of the upper surface US. In that case,the connector P3 corresponds to the surface of the optical adjustor DM1in the side opposed to the display panel PNL, and connects the sidesurfaces P11 and P21. In the example depicted, the connector P3corresponds to a curved surface of the optical adjustor DM1. Note thatthe optical adjustor DM1 may be disposed in a part of the upper surfaceUS.

In the example of FIG. 11, the optical adjustor DM1 is a light diffusingmaterial. For example, the optical adjustor DM1 is formed of asemi-transparent resin material or a resin material in which diffusionbodies are dispersed in a transparent base material. That is, theconnector P3 is formed of a light diffusing material. Specifically, theside surfaces P11 and P21 are formed of a material which is differentfrom a material used in the connector P3, and the side surfaces P11 andP21 have reflectivity which is different from that of the connector P3.Furthermore, the optical adjustor DM1 which is a light diffusingmaterial has a haze value which is less than that of the light diffusinglayer DP.

As can be understood from the above, the optical adjustor DM1 isdisposed in the upper surface US, and thus, light from the light sourceLS is suitably diffused by entering the optical adjustor DM1 and theappearance of bright line by local light concentration can besuppressed. Furthermore, the light diffused by the light diffusing layerDP enters the optical adjustor DM1 and is suitably scattered. Thereby,the direct reflection on the upper surface US is suppressed, the amountof light redirected to the light diffusing layer DP can be decreased,and the appearance of bright line can be suppressed. Note that theconnector P3 may be formed as a rough surface for light diffusion.

FIG. 12 is a perspective view of another example of the structure of thepartition PT in a disassembled manner.

In the example of FIG. 12, each of the ridges RG1 and RG2 has a recessCC and a projection CV. The recesses CC of the ridges RG1 and RG2 aredisposed at crossing points of the ridges RG1 and RG2.

FIG. 13 is a cross-sectional view of another example of the structure ofthe partition PT, taken along line D-E of FIG. 5. FIG. 13 shows across-sectional view of the ridge RG2, taken along line D-E when thepartition PT is formed in the shape shown in FIG. 12, and, in order toclarify their relative positions, the light sources LS1 and LS2, andside surfaces P11 and P13 of the light guide are depicted by dottedlines. As shown, the ridge RG2 includes the recess CC and projection CV.For example, the projection CV projects the most at a mid-positionbetween adjacent recesses CC and is close to the light diffusing layerDP. Note that, although the cross-sectional view of the ridge RG2 willbe explained here; the cross-sectional view of the ridge RG1 is thesame.

As can be understood from the above, the recess CC formed at thecrossing point of the ridges RG1 and RG2, and thus, the light from eachlight source reaches the position directly above the crossing point, andthe appearance of dim line can be suppressed.

FIG. 14 is a cross-sectional view of another example of the structure ofthe partition PT, taken along line A-B of FIG. 5. As compared to theexample of FIG. 11, the structure of FIG. 14 has a different opticaladjustor DM2.

The optical adjustor DM2 is disposed on the upper surface US. In theexample depicted, the optical adjustor DM2 is a sheet extending from theupper surface US to the position opposed to the light sources LS1 andLS2. In the example depicted in FIG. 14, the optical adjustor DM2 is alight diffusing material. Furthermore, the optical adjustor DM2 which isa light diffusing material has a haze value which is less than that ofthe light diffusing layer DP.

With the optical adjustor DM2 as a sheet, the light from the lightsource LS propagates within the optical adjustor DM2 and is diffused tothe upper surface US of the partition PT. That is, the light is guidedto the position where a dim line may appear and the light is diffused inthe position where a bright line may appear. In addition, since theoptical adjustor DM2 has a haze value which is less than that of thelight diffusing layer DP, the direct reflection by the upper surface UScan be suppressed. Thus, unevenness in the brightness in the ridges RG1and RG2 can be suppressed.

FIG. 15 is a cross-sectional view of another example of the structure ofthe partition PT, taken along line A-B of FIG. 5. As compared to theexample of FIG. 11, the structure of FIG. 15 includes a differentoptical adjustor DM3.

The optical adjustor DM3 is disposed in the upper surface US and doesnot extend in the position opposed to the light sources LS1 and LS2. Inthe example of FIG. 15, the optical adjustor DM3 is a light diffusingmaterial. Here, the optical adjustor DM3 includes the first surface P31,second surface P32, and third surface P33 as the connector P3; however,as in the optical adjustor DM1 of FIG. 11, the connector P3 may be acurved surface. That is, the connector P3 is formed of a light diffusingmaterial. Specifically, the side surfaces P11 and P21 are formed of amaterial which is different from a material used in the connector P3,and the side surfaces P11 and P21 have reflectivity which is differentfrom that of the connector P3. Furthermore, the optical adjustor DM3which is a light diffusing material has a haze value which is less thanthat of the light diffusing layer DP.

With the above structure, the same advantages explained with referenceto FIG. 14 can be achieved.

FIG. 16 is a cross-sectional view of another example of the structure ofthe partition PT, taken along line A-B of FIG. 5. As compared to theexample of FIG. 15, the structure of FIG. 16 includes a differentoptical adjustor DM4.

In the example of FIG. 16, the optical adjustor DM4 is a light diffusingmaterial. For example, the optical adjustor DM4 is formed of a blackresin material or a material reflectivity of which is lower than that ofthe upper surface US. Furthermore, in the example depicted, the opticaladjustor DM2 is disposed in the entire surface US; however, it may bedisposed in a part of the upper surface US. Furthermore, the opticaladjustor DM4 includes the first surface P31, second surface P32, andthird surface P33 as the connector P3; however, as in the opticaladjustor DM1 of FIG. 11, the connector P3 may be a curved surface. Thatis, the connector P3 is formed of a light absorbing material. That is,the side surfaces P11 and P21 are formed of a material which isdifferent from that of the connector P3 and the reflectivity of the sidesurfaces P11 and P21 is different from that of the connector P3.

With the optical adjustor DM4 as a light absorbing material disposed inthe upper surface US, the optical adjustor DM4 absorbs the light and theappearance of bright line in the ridges RG1 and RG2 can be suppressed.

FIG. 17 is a plan view showing another example of the arrangement of theoptical adjustor DM4 in the ridges RG1 and RG2. In the example of thearrangement of FIG. 17, the optical adjustor DM4 is formed as dots.

The upper surface US of the partition PT includes, in a plan view, theridge RG1 extending in the first direction X and the ridge RG2 extendingin the second direction Y. The ridges RG1 and RG2 cross each other in alattice.

In the example depicted, the optical adjustor DM4 is arranged as dots inthe upper surface US. In FIG. 17(a), dots of the optical adjustor DM4are arranged in the ridges RG1 and RG2 in even density. In FIG. 17(b),dots of the optical adjustor DM4 are arranged tightly in the ridge RG2as compared to the ridge RG1 and the crossing point of the ridges RG1and RG2.

As explained with reference to FIG. 16, the optical adjustor DM4 isformed of a light absorbing material. Thus, in a position where a brightline may appear, the optical adjustor DM4 as dots should be arranged ina tighter manner, and in a position where a dim line may appear, theoptical adjustor DM4 should not be arranged. In consideration of such acase, the optical adjustor DM4 as dots may be disposed in at least oneof the ridges RG1 and RG2.

For example, in the example of FIG. 17(b), a bright line tends to appearin the ridge RG2 between light sources LS adjacent to each other in thefirst direction X than in the ridge RG1 between light sources LSadjacent to each other in the second direction Y, and dots of tighterdensity are arranged in the ridge RG2 than are in the ridge RG1.

Furthermore, if there is gradation in the distribution of brightness inthe ridges RG1 and RG2, the optical adjustor DM4 should preferably bearranged to sequentially vary the density of dots. That is, the opticaladjustor DM4 formed as dots may have periodically different densities.

For example, as in FIG. 17(b), the dot density on the ridge RG2 alongthe second direction Y becomes less in the crossing point with the ridgeRG1 and becomes more between light sources LS adjacent to each other inthe first direction X.

In such an example of arrangement, the advantages explained withreference to FIG. 16 can be achieved.

FIG. 18 is a plan view of another example of the arrangement of theoptical adjustor DM4 in the ridges RG1 and RG2.

In the example depicted, the optical adjustor DM4 is arranged asstripes. The optical adjustor DM4 includes a first part DM41 and asecond part DM42 as stripes. The first part DM41 extends in the firstdirection X and is arranged in the ridge RG1. The second part DM42extends in the second direction Y and is arranged in the ridge RG2. Inthe example depicted, the first part DM41 has a width W11 along thesecond direction Y which is less than a width W12 of the ridge RG1 inthe second direction Y; however, it may be set to be equal to or lessthan the width W12 of the ridge RG1. Similarly, the second part DM42 hasa width W21 along the first direction X which is less than a width W22of the ridge RG1 in the first direction X; however, it may be set to beequal to or less than the width W22 of the ridge RG2. The first partDM41 and the second part DM42 cross each other at the crossing points ofthe ridges RG1 and RG2.

Note that, the optical adjustor as stripes may be disposed in at leastone of the ridge RG1 and ridge RG2. Furthermore, in the exampledepicted, one optical adjustor DM4 is arranged in each of the ridges RG1and RG2; however, several optical adjustors DM4 may be arranged.Furthermore, the first part DM41 and the second part DM42 each extend inparallel to the ridges RG1 and RG2; however, they may extend indirections different from the first direction X and the second directionY. The area, number, and extending direction of the optical adjustor DM4in each of the ridges RG1 and RG2 can be changed arbitrarily dependingon required suppressing effects of the bright line. In the exampleillustrated, one optical adjustor is provided on one ridge, but aplurality of optical adjustors may be provided on one ridge.

FIG. 19 is a plan view of another example of the arrangement of theoptical adjustor DM4 in the ridges RG1 and RG2.

In the example depicted, the optical adjustor DM4 is arranged in theentire surface of the ridges RG1 and RG2. Thus, the appearance of brightline can be suppressed in the entire surface of the ridges RG1 and RG2.

FIG. 20 is a plan view of another example of the arrangement of theoptical adjustors DM3 and DM4 in the ridges RG1 and RG2. The opticaladjustor DM3 is depicted as a left-down hatch and the optical adjustorDM4 is depicted as a right-down hatch.

The optical adjustor DM3 is disposed in the ridge RG2. The opticaladjustor DM4 is disposed in the ridge RG1. As can be understood from theabove, depending on purposes such as suppressing the appearance ofbright line or suppressing the appearance of dim line in the ridges RG1and RG2, different optical adjustors can be arranged in the ridges RG1and RG2.

Note that the above-described optical adjustors DM1 to DM3 may bearranged in at least one of the ridges RG1 and RG2 as with the opticaladjustor DM4.

Furthermore, as shown in FIGS. 11 and 14 to 20, in the structure wherean optical adjustor is arranged in the upper surface US, the opticaladjustor may be adhered to the upper surface US or may be mountedthereon. For example, if the optical adjustor is a sheet, the sheet mayhave a rough surface to be opposed to the display panel PNL or may havea hole structure. Furthermore, the optical adjustor may be formed in theupper surface US through methods such as coating, deposition, orplating.

In FIG. 21, an example of the application of the display device DSP inthe present embodiment is shown. In the example depicted, the displaydevice DSP is a head up display using a windshield of a vehicle as animage projection screen SCR. The projection screen SCR is not limited toa windshield and a combiner may be used.

The display device DSP includes an illumination device IL, display panelPNL, optical system OP, and projector PJ.

The illumination device IL includes, as described above, several lightsources arranged in the rear surface of the display panel PNL forilluminating the display panel PNL. The details of the illuminationdevice IL and the display panel PNL are explained above and theexplanation thereof is omitted.

The optical system OP includes one or more mirrors which lead light(display light) from the display panel PNL to the projector PJ. Theprojector PJ projects the light led by the optical system OP to theprojection screen SCR. As such a projector PJ, a concave mirror isapplicable.

As described above, the controller 10 drives the display panel PNL onthe basis of the image data and displays an image in the display areaDA. The controller 10 selects necessary brightness in each subillumination area to turn on the light sources of the sub illuminationareas with predetermined brightness. Thereby, a user 200 using thedisplay device DSP can recognize a virtual image 201 in front of theprojection screen SCR.

As can be understood from the above, the present embodiment can presenta display device which can suppress degradation in display quality.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. An illumination device comprising: a first lightsource; a second light source; a third light source; a first partitionarranged between the first light source and the second light source andincluding a first side surface facing the first light source, a secondside surface facing the second light source, and a first connectorconnecting the first side surface and the second side surface, and asecond partition arranged between the first light source and the thirdlight source and including a third side surface facing the first lightsource, a fourth side surface facing the third light source, and asecond connector connecting the third side surface and the fourth sidesurface, wherein the first partition includes a first optical adjustoron the first connector, the second partition includes a second opticaladjustor on the second connector, and a first density of the firstoptical adjustor is different from a second density of the secondoptical adjustor.
 2. The illumination device of claim 1, wherein thefirst density of the first optical adjustor is higher than the seconddensity of the second optical adjustor.
 3. The illumination device ofclaim 1, wherein the first light source and the second light source arearranged in a first direction, and the first light source and the thirdlight source are arranged in a second direction crossing the firstdirection.
 4. The illumination device of claim 1, wherein the firstoptical adjustor and the second optical adjustor diffuse light.
 5. Theillumination device of claim 1, wherein the first optical adjustor andthe second optical adjustor absorb light.
 6. The illumination device ofclaim 1, further comprising, a light diffusing layer opposed to thefirst light source, the second light source, the third light source, thefirst connector, and the second connector.
 7. An optical devicecomprising: a liquid crystal device; an illumination device comprising:a first light source; a second light source; a third light source; afirst partition arranged between the first light source and the secondlight source and including a first side surface facing the first lightsource, a second side surface facing the second light source, and afirst connector connecting the first side surface and the second sidesurface, and a second partition arranged between the first light sourceand the third light source and including a third side surface facing thefirst light source, a fourth side surface facing the third light source,and a second connector connecting the third side surface and the fourthside surface, wherein the first partition includes a first opticaladjustor on the first connector, the second partition includes a secondoptical adjustor on the second connector, and a first density of thefirst optical adjustor is different from a second density of the secondoptical adjustor.
 8. The optical device of claim 7, wherein the firstdensity of the first optical adjustor is higher than the second densityof the second optical adjustor.
 9. The optical device of claim 7,wherein the first light source and the second light source are arrangedin a first direction, and the first light source and the third lightsource are arranged in a second direction crossing the first direction.10. The optical device of claim 7, wherein the first optical adjustorand the second optical adjustor diffuse light.
 11. The optical device ofclaim 7, wherein the first optical adjustor and the second opticaladjustor absorb light.
 12. The optical device of claim 7, furthercomprising, a light diffusing layer disposed between the liquid crystaldevice and the illumination device.
 13. An optical device comprising: aliquid crystal device; an illumination device comprising: a first lightsource; a second light source; a third light source; a first partitionarranged between the first light source and the second light source andincluding a first side surface facing the first light source, a secondside surface facing the second light source, and a first connectorconnecting the first side surface and the second side surface, and asecond partition arranged between the first light source and the thirdlight source and including a third side surface facing the first lightsource, a fourth side surface facing the third light source, and asecond connector connecting the third side surface and the fourth sidesurface, wherein the first partition includes a first optical adjustoron the first connector, the second partition includes a second opticaladjustor on the second connector, the first optical adjustor is arrangedin different densities from place to place, and the second opticaladjustor is arranged in different densities from place to place.
 14. Theoptical device of claim 13, wherein the first light source and thesecond light source are arranged in a first direction, and the firstlight source and the third light source are arranged in a seconddirection crossing the first direction.
 15. The optical device of claim13, wherein the first optical adjustor and the second optical adjustordiffuse light.
 16. The optical device of claim 13, wherein the firstoptical adjustor and the second optical adjustor absorb light.
 17. Theoptical device of claim 13, further comprising, a light diffusing layeropposed to the first light source, the second light source, the thirdlight source, the first connector, and the second connector.